Skip to main content

Unfortunately we don't fully support your browser. If you have the option to, please upgrade to a newer version or use Mozilla Firefox, Microsoft Edge, Google Chrome, or Safari 14 or newer. If you are unable to, and need support, please send us your feedback.

Publish with us
Lateral Branch of Posterior Ramus of Fourth Lumbar Nerve (Left)
Nervous System

Lateral Branch of Posterior Ramus of Fourth Lumbar Nerve (Left)

Ramus posterior lateralis nervi lumbalis quarti

Read more

Quick Facts

Origin: Posterior ramus of fourth lumbar nerve.

Course: Crosses over the subjacent L5 transverse process to course laterally deep to longissimus and iliocostalis parts of the lumbar erector spinae. It remains entirely intramuscular.

Branches: None.

Supply: Motor innervation to longissimus and iliocostalis muscles.

Complete Anatomy
The world's most advanced 3D anatomy platform
Try it for Free


After the posterior ramus of the fourth lumbar nerve has traversed through intertransverse ligament and medial intertransverse muscle, a large lateral branch is given off, between the fourth and fifth lumbar vertebrae. In addition, the small medial neuronal branch is given off.


The lateral branch crosses the subjacent fourth lumbar transverse process and pursues a sinuous course caudally, laterally, and dorsally through the longissimus and iliocostalis components of lumbar erector spinae muscle. Often, the muscular branch to longissimus comes off from the posterior ramus as a separate intermediate branch. These forms interneuronal loops with the corresponding branches of other posterior rami to innervate the muscle. The lateral branch of fourth lumbar nerve remains entirely intramuscular throughout its course (Bogduk, 2016, Boelderl et al., 2002).


There are no named branches.

Supplied Structures

The lateral branch supplies the longissimus and iliocostalis components of the lumbar erector spinae muscle.

List of Clinical Correlates



Boelderl, A., Daniaux, H., Kathrein, A. and Maurer, H. (2002) 'Danger of damaging the medial branches of the posterior rami of spinal nerves during a dorsomedian approach to the spine', Clin Anat, 15(2), pp. 77-81.

Bogduk, N. (2016) 'Functional anatomy of the spine', Handb Clin Neurol, 136, pp. 675-88.

Learn more about this topic from other Elsevier products

Lumbar Nerves

ScienceDirect image

The ileoinguinal nerve arises from the first lumbar nerve, giving branches to the obliquus internus muscle and to the skin covering the mons pubis and labia majora.

Explore on ScienceDirect(opens in new tab/window)

Complete Anatomy

The world's most advanced 3D anatomy platform

Complete Anatomy